Heretofore, buccal tubes for receiving the distal ends of a lip bumper or a face bow have been generally sized with a uniformly dimensioned opening between the mesial and distal and which closely receives the lip bumper or face bow end such as shown in U.S. Pat. No. 4,378,210.
The placement of a lip bumper or a face bow is nearly always done by the patient. The only exception is when the patient is visiting his orthodontist and the orthodontist is providing instructions on how to place the appliance. Since the face bow or lip bumper tubes have always been sized to closely receive the face bow or lip bumper ends, difficulty is often experienced by the patient in placement of the lip bumper or face bow as the size of the wire used for a lip bumper or a face bow is substantially equal to the size of the opening in the buccal tube which receives that end. These difficulties often lead to causing injuries in the mouth where the distal ends of the lip bumper or face bow impingedly engages and injures the tissues of the mouth.
It has also been desirable for many years to distally offset molar headgear tubes, but difficulty is experienced in mounting because the headgear face bows include arms or ends that are too stiff to insert into the standard molar tubes and then the ends of the arms must be bent to permit insertion.
It has been known to taper part of the inner end of the buccal tube such as shown in FIG. 3 of U.S. Pat. No. 3,874,080. Such a structure produces a lip or edge along the opening which could produce a hangup on insertion of a lip bumper or face bow end and result in accidental "bounce back" and then an injury to the soft tissues in the mouth. When it is considered that the patient must be responsible for insertion of the distal ends of a lip bumper or face bow, and further that the patient is not an expert in handling such an operation as opposed to a professional, the chance of accidental injury is substantially greater. Therefore, it is important to reduce this hazard in order to improve the quality of orthodontic treatment and the cooperation of a patient, and safer to place a lip bumper or face bow by the patient particularly when one or both molars are adversely rotated. It will be appreciated that those patients sensitive to mouth injury and wanting to avoid such injury may not use the lip bumper or face bow, thereby completely defeating the purpose of these appliances and ultimately lengthening or completely defeating orthodontic treatment.